U.S. Pat. Nos. 4,362,272 and 4,467,967 generally disclose a type of manure spreader that includes a V-shaped tank for containing manure, an auger conveyor in the bottom of the tank for moving manure toward an opening in one of the sidewalls of the tank, and an expeller mounted adjacent the opening in the one tank sidewall to discharge manure in a lateral spread pattern away from the tank.
The expeller of U.S. Pat. No. 4,362,272 consists of a plurality of scoop sections welded to a rotatable shaft to form a rigid assembly which is quiet during operation and generally durable. A problem exists with this type of expeller, however, if rocks are inadvertently loaded into the tank with manure and then subsequently discharged with the manure by the expeller. The problem is that these rocks often contact the expeller scoop sections in a manner that causes permanent deformation of the expeller. Should the expeller become severely deformed it will have to be replaced with a new expeller. Such replacement of a deformed expeller is very expensive and time consuming.
The expeller of U.S. Pat. No. 4,467,967 is comprised of a set of blades with each blade pivotally connected to a rotatable shaft. While this type of expeller virtually eliminates the above mentioned problem of deformation of the expeller due to rocks, the pivotal blades are noisy during operation and the pivot connections for the blades are expensive and have limited durability.
Therefore, it is an object of the present invention to provide an improved expeller for the type of manure spreader generally disclosed in U.S. Pat. Nos. 4,362,272 and 4,467,967 which will not be severely deformed by contacting foreign objects such as rocks in the manure but will be quiet in operation and durable.
The improved expeller of the present invention comprises paddles fastened to support members that are fixed to a rotatable shaft by first and second fastener means. In the preferred embodiment of the improved expeller, the first fastener means constitutes shear bolts which are designed to fail when a predetermined load is exerted on the paddle. If these shear bolts fail under the predetermined load, the paddle may be pivoted about the second fastener means from an extended position to a retracted position. The second fastener means will hold the paddle in the retracted position until it is manually returned to the extended position for installation of new shear bolts.